Mack T2090 9 Speed Transmission Questions

[BOBWhite]

Might be a dumb question but there are two different shift patterns for the Mack 9 speed, did they change anything mechanically when they changed this? Ive driven the old pattern of 9 speed but should I be shifting it in the new pattern? If you can change how you shift in the pattern then what the difference between a 10 speed and a 9 speed?  Its probably all in the high low shift box but what's is best for this transmission? Thanks 

[theakerstwo]

1 hour ago, BOBWhite said:

Might be a dumb question but there are two different shift patterns for the Mack 9 speed, did they change anything mechanically when they changed this? Ive driven the old pattern of 9 speed but should I be shifting it in the new pattern? If you can change how you shift in the pattern then what the difference between a 10 speed and a 9 speed?  Its probably all in the high low shift box but what's is best for this transmission? Thanks 

Same trans but new shift pattern will let the rear box range at a slower road speed saving the shift clutchs i think.

[Joey Mack]

how old is the (old) Mack 9spd?  I think there were some that had lo-lo and3 on the low side and 5 on the top. the newer 9 speeds shift similar to a 10 spd, but in high range you go up for 6th instead of over too you and down..  8ll is similar..  hell the 13 speed is the same pattern but without the splitter for the top 4 gears... jojo

Edited May 14, 2022 by Joey Mack

[BOBWhite]

1985 so it's the same pattern as an eaton 9 speed. But would it be better for the transmission to shift it like the new pattern or should I stick with the old one?

Hope that makes more sense, Thanks

Edit: Oops Its not the same as the eaton 9 speed, the 3,4 and 7,8 are switched on the mack 

Edited May 15, 2022 by BOBWhite

[Joey Mack]

Bob.. the second shift pattern is a box pattern..  top gear will have the stick up and to the right, at the dash board..  if you shift this one like the other one you will grind into the gear (if you get it) and then the truck will slow down.... it's a down shift not an up shift...  I drove an International 8100 with this same shift pattern as the second picture..  2 different patterns..  if i remember right ,  the second tranny doesnt have the lever in  the shift cover that lets you shift the 'H' pattern... i'm having a brain fart.. the second pattern can be skip shifted which makes it an 'X' pattern... confused yet??  I almost am...  anyway..  if the second pattern is what you are currently driving,  get used to it...   and yes like me, when you get into an 'H' pattern truck you will probably scrub a gear or 3..    then when you go back to 'box' pattern... well...      I may have just rambled on this instead of helping..  jojo

[theakerstwo]

I remember when the pattern was 5 in low range and it was a over drive 9 speed with 5th gear down to the botton right.Mack came out with a update saying on same trans to start coming out of 4th at the top right and range into hi and go to 1st which is bottom left saying the range was being made at a slower speed saving the hi/low clutches.I had one so i started to shift that way.But on a 18 speed in my CH i could not make sense in this.This is a mack trans i am talking about.The photo on the left is the updated shifting.You are staying out of over drive in low range.

[BOBWhite]

Ok I really don't mean to beat a dead horse here but I found this thread here: https://www.bigmacktrucks.com/topic/28092-t2090/

specifically this part: 

I know it's probably up to the whoever's paying for the transmission rebuild but it still makes me wonder which pattern is better for the transmission in the long run. If the old pattern transmission and the new pattern transmission are mechanically and internally the same than I'd say shift it in the new pattern If it goes smoother, 4th low always sucked to get into anyways.